Tab Network Controller от Mochizilla

English (US)
This extension will automatically disable network connections for all background tabs. Only the current, active tab will be able to access the internet. Use this to disable background pages, apps, ads and any superfluous networking activity, without fully closing or suspending background tabs. Especially useful when working in a web app that has a large number of network connections.

The extension can be disabled or enabled in the interface.

Note: Tabs opened using [right-click] -> "Open Link in New Tab" will not properly load in the background if this extension is enabled. You must refresh the page after switching to those tabs.